OFFSET
0,2
COMMENTS
For n > 1, a(n) is a multiple of 6. More generally, phi(n^(2*k) + n^k + 1) is a multiple of 6*k for all n > 1 and k >= 1. - Max Alekseyev, Sep 24 2024
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..10000 (terms n = 1..1000 from Harry J. Smith)
FORMULA
MATHEMATICA
Table[EulerPhi[n^2+n+1], {n, 60}] (* Harvey P. Dale, May 06 2013 *)
PROG
(PARI) { for (n=1, 1000, write("b066791.txt", n, " ", eulerphi(n^2 + n + 1)) ) } \\ Harry J. Smith, Mar 27 2010
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Jan 18 2002
EXTENSIONS
a(0)=1 prepended by Alois P. Heinz, Sep 24 2024
STATUS
approved